2000-03-29 16:38:44 +04:00
|
|
|
<HTML><HEAD><TITLE>
|
|
|
|
|
<TT>ntpd</TT> - Network Time Protocol (NTP) daemon
|
|
|
|
|
</TITLE></HEAD><BODY><H3>
|
|
|
|
|
<TT>ntpd</TT> - Network Time Protocol (NTP) daemon
|
|
|
|
|
</H3><HR>
|
|
|
|
|
|
|
|
|
|
<H4>Synopsis</H4>
|
|
|
|
|
|
|
|
|
|
<TT>ntpd [ -aAbdm ] [ -c <I>conffile</I> ] [ -f <I>driftfile</I> ] [ -g
|
|
|
|
|
] [ -k <I>keyfile</I> ] [ -l <I>logfile</I> ] [ -p <I>pidfile</I> ] [ -r
|
|
|
|
|
<I>broadcastdelay</I> ] [ -s <I>statsdir</I> ] [ -t <I>key</I> ] [ -v
|
|
|
|
|
<I>variable</I> ] [ -V <I>variable</I> ] [ -x ]</TT>
|
|
|
|
|
|
|
|
|
|
<H4>Description</H4>
|
|
|
|
|
|
|
|
|
|
<TT>ntpd</TT> is an operating system daemon which sets and maintains the
|
|
|
|
|
system time-of-day in synchronism with Internet standard time servers.
|
|
|
|
|
<TT>ntpd</TT> is a complete implementation of the Network Time Protocol
|
|
|
|
|
(NTP) version 4, but also retains compatibility with version 3, as
|
|
|
|
|
defined by RFC-1305, and version 1 and 2, as defined by RFC-1059 and
|
|
|
|
|
RFC-1119, respectively. <TT>ntpd</TT> does most computations in 64-bit
|
|
|
|
|
floating point arithmetic and does relatively clumsy 64-bit fixed point
|
|
|
|
|
operations only when necessary to preserve the unltimate precision,
|
|
|
|
|
about 232 picoseconds. While the ultimate precision, is not achievable
|
|
|
|
|
with ordinary workstations and networks of today, it may be required
|
|
|
|
|
with future nanosecond CPU clocks and gigabit LANs.
|
|
|
|
|
|
|
|
|
|
<P>The daemon can operate in any of several modes, including symmetric
|
|
|
|
|
active/passive, client/server broadcast/multicast and manycast. A
|
|
|
|
|
broadcast/multicast or manycast client can discover remote servers,
|
|
|
|
|
compute server-client propagation delay correction factors and configure
|
|
|
|
|
itself automatically. This makes it possible to deploy a fleet of
|
|
|
|
|
workstations without specifying configuration details specific to the
|
|
|
|
|
local environment.
|
|
|
|
|
|
|
|
|
|
<P>Ordinarily, <TT>ntpd</TT> reads the <TT>ntp.conf</TT> configuration
|
|
|
|
|
file at startup time in order to determine the synchronization sources
|
|
|
|
|
and operating modes. It is also possible to specify a working, although
|
|
|
|
|
limited, configuration entirely on the command line, obviating the need
|
|
|
|
|
for a configuration file. This may be particularly appropriate when the
|
|
|
|
|
local host is to be configured as a broadcast/multicast client or
|
|
|
|
|
manycast client, with all peers being determined by listening to
|
|
|
|
|
broadcasts at run time.
|
|
|
|
|
|
|
|
|
|
<P>If NetInfo support is built into <TT>ntpd</TT>, then <TT>ntpd</TT>
|
|
|
|
|
will attempt to read its configuration from the NetInfo if the default
|
|
|
|
|
ntp.conf file cannot be read and no file is specified by the <TT>-c</TT>
|
|
|
|
|
option.
|
|
|
|
|
|
|
|
|
|
<P>Various internal <TT>ntpd</TT> variables can be displayed and
|
|
|
|
|
configuration options altered while the daemon is running using the
|
|
|
|
|
<TT><A HREF="ntpq.htm">ntpq</A></TT> and <TT><A
|
|
|
|
|
HREF="ntpdc.htm">ntpdc</A></TT> utility programs.
|
|
|
|
|
|
|
|
|
|
<P>When <TT>ntpd</TT> starts it looks at the value of <TT>umask</TT>,
|
|
|
|
|
and if it's zero <TT>ntpd</TT> will set the <TT>umask</TT> to
|
|
|
|
|
<TT>022</TT>.
|
|
|
|
|
|
|
|
|
|
<H4>Command Line Options</H4>
|
|
|
|
|
|
|
|
|
|
<DL>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-a</TT></DT>
|
|
|
|
|
<DD>Enable authentication mode (default).</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-A</TT></DT>
|
|
|
|
|
<DD>Disable authentication mode.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-b</TT></DT>
|
|
|
|
|
<DD>Synchronize using NTP broadcast messages.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-c <I>conffile</I></TT></DT>
|
|
|
|
|
<DD>Specify the name and path of the configuration file.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-d</TT></DT>
|
|
|
|
|
<DD>Specify debugging mode. This flag may occur multiple times, with
|
|
|
|
|
each occurrence indicating greater detail of display.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-D <I>level</I></TT></DT>
|
|
|
|
|
<DD>Specify debugging level directly.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-f <I>driftfile</I></TT></DT>
|
|
|
|
|
<DD>Specify the name and path of the drift file.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-g</TT></DT>
|
|
|
|
|
<DD>Normally, the daemon exits if the offset exceeds a 1000-s sanity
|
|
|
|
|
limit. This option overrides this limit and allows the time to be set to
|
|
|
|
|
any value without restriction; however, this can happen only once. After
|
|
|
|
|
that, the daemon will exit of the limit is exceeded.
|
|
|
|
|
|
|
|
|
|
<DT><TT>-k <I>keyfile</I></TT></DT>
|
|
|
|
|
<DD>Specify the name and path of the file containing the NTP
|
|
|
|
|
authentication keys.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-l <I>logfile</I></TT></DT>
|
|
|
|
|
<DD>Specify the name and path of the log file. The default is the system
|
|
|
|
|
log facility.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-m</TT></DT>
|
|
|
|
|
<DD>Synchronize using NTP multicast messages on the IP multicast group
|
|
|
|
|
address 224.0.1.1 (requires multicast kernel).</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-p <I>pidfile</I></TT></DT>
|
|
|
|
|
<DD>Specify the name and path to record the daemon's process ID.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-P</TT></DT>
|
|
|
|
|
<DD>Override the priority limit set by the operating system. Not
|
|
|
|
|
recommended for sissies.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-r <I>broadcastdelay</I></TT></DT>
|
|
|
|
|
<DD>Specify the default propagation delay from the broadcast/multicast
|
|
|
|
|
server and this computer. This is necessary only if the delay cannot be
|
|
|
|
|
computed automatically by the protocol.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-s <I>statsdir</I></TT></DT>
|
|
|
|
|
<DD>Specify the directory path for files created by the statistics
|
|
|
|
|
facility.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-t <I>key</I></TT></DT>
|
|
|
|
|
<DD>Add a key number to the trusted key list.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-v <I>variable</I></TT></DT>
|
|
|
|
|
<DT><TT>-V <I>variable</I></TT></DT>
|
|
|
|
|
<DD>Add a system variable listed by default.</DD>
|
|
|
|
|
|
|
|
|
|
<DT><TT>-x</TT></DT>
|
|
|
|
|
<DD>Ordinarily, if the time is to be adjusted more than 128 ms, it is
|
|
|
|
|
stepped, not gradually slewed. This option forces the time to be slewed
|
|
|
|
|
in all cases. Note: Since the slew rate is limited to 0.5 ms/s, each
|
|
|
|
|
second of adjustment requires an amortization interval of 2000 s. Thus,
|
|
|
|
|
an adjustment of many seconds can take hours or days to amortize.</DD>
|
|
|
|
|
</DL>
|
|
|
|
|
|
|
|
|
|
<H4>The Configuration File</H4>
|
|
|
|
|
|
|
|
|
|
The <TT>ntpd</TT> configuration file is read at initial startup in order
|
|
|
|
|
to specify the synchronization sources, modes and other related
|
|
|
|
|
information. Usually, it is installed in the <TT>/etc</TT> directory,
|
|
|
|
|
but could be installed elsewhere (see the <TT>-c <I>conffile</I></TT>
|
|
|
|
|
command line option). The file format is similar to other Unix
|
|
|
|
|
configuration files - comments begin with a <TT>#</TT> character and
|
|
|
|
|
extend to the end of the line; blank lines are ignored. Configuration
|
|
|
|
|
commands consist of an initial keyword followed by a list of arguments,
|
|
|
|
|
some of which may be optional, separated by whitespace. Commands may not
|
|
|
|
|
be continued over multiple lines. Arguments may be host names, host
|
|
|
|
|
addresses written in numeric, dotted-quad form, integers, floating
|
|
|
|
|
point numbers (when specifying times in seconds) and text strings.
|
|
|
|
|
Optional arguments are delimited by <TT>[ ]</TT> in the following
|
|
|
|
|
descriptions, while alternatives are separated by <TT>|</TT>. The
|
|
|
|
|
notation <TT>[ ... ]</TT> means an optional, indefinite repetition of
|
|
|
|
|
the last item before the <TT>[ ... ]</TT>.
|
|
|
|
|
|
|
|
|
|
<P>See the following pages for configuration and control options. While
|
|
|
|
|
there is a rich set of options available, the only required option is
|
|
|
|
|
one or more <TT>server, peer,</TT> <TT>broadcast</TT> or
|
|
|
|
|
<TT>manycastclient </TT>commands described in the Configuration Options
|
|
|
|
|
page. The <A HREF="notes.htm">Notes on Configuring NTP and Setting up a
|
|
|
|
|
NTP Subnet </A>page contains an extended discussion of these options.
|
|
|
|
|
|
|
|
|
|
<P><A HREF="confopt.htm">Configuration Options</A>
|
|
|
|
|
<BR><A HREF="authopt.htm">Authentication Options</A>
|
|
|
|
|
<BR><A HREF="monopt.htm">Monitoring Options</A>
|
|
|
|
|
<BR><A HREF="accopt.htm">Access Control Options</A>
|
|
|
|
|
<BR><A HREF="clockopt.htm">Reference Clock Options</A>
|
|
|
|
|
<BR><A HREF="miscopt.htm">Miscellaneous Options</A>
|
|
|
|
|
|
|
|
|
|
<H4>Files</H4>
|
|
|
|
|
|
|
|
|
|
<TT>/etc/ntp.conf</TT> - the default name of the configuration file
|
|
|
|
|
<BR><TT>/etc/ntp.drift</TT> - the default name of the drift file
|
|
|
|
|
<BR><TT>/etc/ntp.keys</TT> - the default name of the key file
|
|
|
|
|
|
|
|
|
|
<H4>Bugs</H4>
|
|
|
|
|
|
|
|
|
|
<TT>ntpd</TT> has gotten rather fat. While not huge, it has gotten
|
|
|
|
|
larger than might be desireable for an elevated-priority daemon running
|
|
|
|
|
on a workstation, particularly since many of the fancy features which
|
|
|
|
|
consume the space were designed more with a busy primary server, rather
|
|
|
|
|
than a high stratum workstation, in mind.
|
|
|
|
|
|
2000-04-22 20:46:49 +04:00
|
|
|
<hr><a href=index.htm>Home</a><address><a
|
2000-03-29 16:38:44 +04:00
|
|
|
href=mailto:mills@udel.edu> David L. Mills <mills@udel.edu></a>
|
|
|
|
|
</address></a></body></html>
|
